Non-direct parallel gan power module topology and dc-dc converter

Abstract

The application belongs to the technical field of power semiconductor device application, and discloses a non-direct parallel GaN power module topology structure and a DC-DC converter, which comprises: at least two independent GaN power units, each of which comprises a GaN half-bridge circuit, and the GaN power units are not directly electrically connected in parallel; a power transmission channel corresponding to each GaN power unit, the input end of each power transmission channel is connected with the output end of the corresponding GaN power unit, and the power transmission channels are not directly electrically connected; a power superposition unit connected with the output ends of the power transmission channels respectively, used for superimposing the power transmitted by the power transmission channels and then outputting to a load; and a control unit connected with the GaN power units respectively, used for sending control signals to the GaN power units. The application can eliminate the problems of dynamic resistance degradation and uneven current caused by the direct parallel connection of GaN devices.

Description

Technical Field

[0001] This application relates to the field of power semiconductor device application technology, and in particular, it relates to a non-directly parallel GaN power module topology and a DC-DC converter. Background Technology

[0002] Gallium nitride (GaN) power devices, as a typical representative of third-generation semiconductor materials, possess excellent characteristics such as wide bandgap, high critical field strength, and high electron saturation velocity. Leveraging their high frequency, high efficiency, and high power density, they are increasingly widely used in numerous fields, including new energy vehicles, aviation power supplies, data center power supplies, and 5G communication base stations. In particular, with the rapid development of the low-altitude economy, tiltrotor drones, due to their dual advantages of vertical takeoff and landing and efficient cruise, have become an important development direction in the aviation field. High-power-density DC-DC converters, as core components of range-extended tiltrotor drones, impose stringent requirements on power density (≥12kW / L), making gallium nitride power devices an ideal choice due to their high frequency and high efficiency.

[0003] In high-power applications, the current carrying capacity of a single GaN device is often insufficient to meet system requirements, necessitating the parallel connection of multiple GaN devices to increase the overall current rating. However, GaN devices face a critical challenge in high-power systems: dynamic resistance degradation. Dynamic resistance degradation refers to the phenomenon where the on-resistance of a GaN device gradually increases with the number of switching operations due to the trapping effect during high-voltage switching. When multiple GaN devices are directly connected in parallel, the degree of dynamic resistance degradation varies among the devices, causing on-resistance drift and resulting in severe current unevenness. Some devices experience excessive thermal stress due to the high current, leading to increased junction temperature and further exacerbating dynamic resistance degradation, creating a vicious cycle of positive feedback and ultimately causing device failure, severely impacting system reliability and lifespan.

[0004] Therefore, how to overcome the dynamic resistance degradation and current unevenness caused by direct parallel connection of GaN devices, and provide a new topology that can fundamentally solve the above problems, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This application provides a non-directly parallel GaN power module topology and a DC-DC converter, which can eliminate the problems of dynamic resistance degradation and current unevenness caused by direct parallel connection of GaN devices.

[0006] The solution presented in this application is implemented through the following steps.

[0007] In a first aspect, examples of this application disclose a non-directly parallel GaN power module topology, comprising: At least two independent GaN power units, each GaN power unit includes a GaN half-bridge circuit, and there is no direct electrical parallel connection between the GaN power units; Each GaN power unit has a power transmission channel corresponding to it. The input terminal of each power transmission channel is connected to the output terminal of the corresponding GaN power unit, and there is no direct electrical connection between the power transmission channels. A power superposition unit is connected to the output terminal of each of the power transmission channels, and is used to superimpose the power transmitted by each power transmission channel and output it to the load; The control unit is connected to each of the GaN power units and is used to send control signals to each of the GaN power units.

[0008] By constructing independent GaN power units and independent power transmission channels, with no direct electrical parallel connection between the units, a circuit structure of switch branch—resonant inductor—bus node is formed. This achieves branch impedance decoupling and eliminates the problems of on-resistance drift and parallel current imbalance caused by dynamic resistance degradation. Even if the on-resistance of a single GaN power unit drifts due to dynamic resistance degradation, this change will not affect other units through the electrical path, thus avoiding on-resistance drift and parallel current imbalance at the topology level. At the same time, the control unit does not require complex current sharing algorithms; simple temperature equalization can achieve natural current sharing among the units, significantly reducing the complexity and cost of the control system.

[0009] In the non-directly parallel GaN power module topology described above, optionally, the power transmission channel includes a high-frequency transformer or a coupled inductor; wherein the high-frequency transformer and the coupled inductor are formed by magnetic cores and windings.

[0010] By using high-frequency transformers or coupled inductors as the core components of the power transmission channel, high-frequency energy transmission and electrical isolation can be effectively achieved. At the same time, magnetic integration technology can further reduce the size of magnetic components and improve the power density of the system.

[0011] In the non-directly parallel GaN power module topology described above, optionally, the power superposition unit is a bus connection node of a high-frequency transformer, and the output terminals of each power transmission channel are connected in parallel to the bus connection node; wherein, the output terminals of each power transmission channel are respectively connected to different winding taps or different primary windings of the primary winding of the high-frequency transformer, and the secondary winding of the high-frequency transformer is used to connect the load.

[0012] The superposition of multiple power sources is achieved by using a single connection node on the primary side of a high-frequency transformer. The structure is simple and easy to implement. The transformer also provides electrical isolation to ensure safe isolation between the primary power unit and the secondary load.

[0013] In the non-directly parallel GaN power module topology described above, optionally, the GaN half-bridge circuit includes an upper GaN power switch and a lower GaN power switch, wherein the gates of the upper and lower GaN power switches respectively receive complementary control signals from the control unit.

[0014] By employing a half-bridge topology and complementary drive signals, it can efficiently convert DC input into high-frequency AC energy and achieve soft switching through a resonant network, thereby reducing switching losses.

[0015] In the non-directly parallel GaN power module topology described above, optionally, the control unit includes: The main controller is used to calculate the total power command according to the load demand and distribute the total power command to multiple sub-controllers according to a preset strategy; wherein, the preset strategy is a power equalization distribution strategy executed based on the temperature feedback of each GaN power unit; Each of the sub-controllers controlling the GaN power units is used to generate corresponding drive pulses according to the assigned power command; wherein, the drive pulse is used to control the upper GaN power switch and the lower GaN power switch of a GaN half-bridge circuit.

[0016] In the non-directly parallel GaN power module topology described above, optionally, each GaN power unit includes a protection circuit for monitoring the operating status of the corresponding GaN power unit and performing protection operations when the operating status is abnormal.

[0017] By setting up independent protection circuits, each power unit has the ability to self-heal from faults, preventing the failure of a single unit from affecting the normal operation of other units and enhancing the fault tolerance of the system.

[0018] In the non-directly parallel GaN power module topology described above, optionally, the protection circuit includes an overcurrent protection circuit and an overtemperature protection circuit, used to shut down the drive pulse of the corresponding GaN power unit and upload the fault signal to the control unit when an overcurrent or overtemperature fault is detected in any GaN power unit.

[0019] By setting up a dedicated hardware protection circuit, it can respond quickly within microseconds of a fault occurring, effectively protecting power devices from damage, avoiding excessive thermal stress on devices caused by local overcurrent, ensuring uniform heat distribution in each unit, and extending the overall lifespan of the system.

[0020] In the non-directly parallel GaN power module topology described above, optionally, the control unit is also used to update the power allocation command based on the number and capacity of the remaining GaN power units that are in normal working condition after receiving a fault signal.

[0021] By setting up protection circuits for protection and fault alarms, the system achieves fault-tolerant operation capability. In high-reliability application scenarios such as aviation power supplies, when a certain unit fails, the system can automatically reconfigure to maintain stable output voltage and ensure that critical loads such as UAVs can return safely. The fault-tolerant design ensures that the failure of a single unit does not affect the continuous operation of the system, greatly improving the mission reliability of the system.

[0022] In the non-directly parallel GaN power module topology described above, optionally, the over-temperature protection circuit includes: A constant temperature source is used to output a target temperature signal according to the control signal from the control unit. A thermal resistor corresponding to each GaN power unit is used to adjust the temperature of each GaN power unit to the target temperature according to the target temperature signal.

[0023] The thermal model constructed using a constant temperature source and thermal resistance enables closed-loop temperature control of each power unit, ensuring that each unit operates within a suitable temperature range and avoiding dynamic resistance degradation differences caused by temperature inconsistencies. This helps achieve current sharing from a thermal management perspective.

[0024] A second aspect of this application provides a DC-DC converter including the non-directly parallel GaN power module topology described in any of the first aspects above.

[0025] By adopting the non-directly parallel GaN power module topology of this application, the problems of dynamic resistance degradation and current unevenness caused by direct parallel connection of GaN devices are effectively solved, significantly improving the reliability and stability of the power supply system and meeting the stringent requirements of aerospace applications for high reliability and high power density. Attached Figure Description

[0026] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this application are illustrated by way of example and not limitation, and the same or corresponding reference numerals denote the same or corresponding parts, wherein: Figure 1 This embodiment provides a schematic diagram of a non-directly parallel GaN power module topology. Figure 2 Provided for this embodiment Figure 1 Enlarged schematic diagram of the input bus and the primary GaN power switch section; Figure 3 This is a schematic diagram of the logic for generating a drive signal provided in this embodiment; Figure 4 This embodiment provides a schematic diagram of a key simulation waveform. Figure 5 Provided for this embodiment Figure 1 Enlarged schematic diagram of the intermediate resonant network and high-frequency transformer section; Figure 6 Provided for this embodiment Figure 1 A magnified schematic diagram of the middle and secondary side synchronous rectification and output filtering section; Figure 7 This is a schematic diagram illustrating the relationship between thermal modeling and heat dissipation in this embodiment. Detailed Implementation

[0027] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0028] To address the dynamic resistance degradation and current imbalance issues caused by direct parallel connection of GaN devices, traditional current sharing methods mainly fall into two categories: active current sharing control and passive current sharing control. Active current sharing control achieves current balance by real-time detection of the current in each parallel branch and adjusting the gate drive delay or duty cycle. This method is complex to control, has limited response speed, and requires high-precision current sampling and high-speed control circuitry, resulting in high costs. Passive current sharing control achieves current sharing by matching device parameters or adding impedance components. This method has high requirements for device consistency and is difficult to adapt to parameter drift caused by dynamic resistance degradation. Overall, traditional current sharing methods rely on complex active control or gate delay matching, making it difficult to fundamentally solve the parallel imbalance problem caused by dynamic resistance drift. This has become a bottleneck restricting the large-scale application of GaN devices in high-reliability aerospace power supplies.

[0029] Based on this, combined Figure 1 and Figure 2 As shown, Figure 1 This is a schematic diagram of a non-directly parallel GaN power module topology. Figure 2 for Figure 1An enlarged schematic diagram of the input bus and the primary-side GaN power switch section; this embodiment provides a non-directly parallel GaN power module topology. Employing a non-directly parallel architecture, power is distributed to multiple independent GaN power units, with no direct parallel connection between the units. This completely eliminates the on-resistance drift and parallel current imbalance problems caused by dynamic resistance degradation. It eliminates the need for complex active current sharing control or gate delay matching, fundamentally solving the inherent defects of traditional parallel schemes.

[0030] For example, a non-directly parallel GaN power module topology includes at least two independent GaN power units, a power transmission channel corresponding to each GaN power unit, a power superposition unit, and a control unit.

[0031] like Figure 1 As shown, the overall circuit topology schematic includes a DC power supply V_dc, series-connected voltage divider resistors R2 / R3 and bus capacitors C1 / C2, primary-side GaN power switches FETD, FETD1 to FETD7 (forming multiple GaN power units), resonant inductors Lr / Lr1 / Lr2 / Lr3 (forming multiple power transmission channels), resonant capacitor Cr, measuring element Am1, high-frequency transformer Tr3 (forming a power superposition unit), coupling capacitor C3, synchronous rectifier switches FETD8 to FETD11, output filter capacitor C, voltage measuring element Vm1, and thermal models Rth and TconstG. On the input side, the voltage divider resistors R2 and R3, along with the bus capacitors C1 and C2, form a split DC bus, supplying power to the primary-side power stage.

[0032] The primary power stage consists of at least two GaN power units composed of multiple sets of two GaN power switching devices connected in series (the two selected in purple on the primary side). The devices are identified as FETD, FETD1, FETD2, FETD3, FETD4, FETD5, FETD6, and FETD7. Among them, FETD and FETD1 form one GaN power unit, FETD2 and FETD3 form one GaN power unit, FETD4 and FETD5 form one GaN power unit, and FETD6 and FETD7 form one GaN power unit. Each GaN power unit is driven by control signals s1 and s2 output by the control unit (not shown in the attached figure).

[0033] It should be further described that the number of GaN power units is determined according to the target output power level. When it is necessary to increase the system power level, it is only necessary to add GaN power units and corresponding power transmission channels, and connect their outputs to the system output terminal to achieve power superposition. This embodiment illustrates a non-directly parallel GaN power module topology with 4 GaN power units.

[0034] The switching branches of each GaN power unit are connected to the resonant capacitor Cr via resonant inductors Lr, Lr1, Lr2, and Lr3, respectively, thus forming a non-direct parallel power bus mode under the impedance isolation of the resonant branches; the resonant current is sampled by the current measuring element Am1 and electrically isolated and voltage transformed by the high-frequency transformer Tr3.

[0035] The transformer Tr3, after being coupled with capacitor C3 in series on its secondary side, enters the synchronous rectification unit. The synchronous rectification is composed of FETD8, FETD9, FETD10, and FETD11. A filter capacitor C is connected in parallel on the output side to form a DC output. The output voltage is sampled by voltage measurement element Vm1 and sent to the Scope for display. Furthermore, to evaluate the thermal characteristics of the power devices, a thermal resistance Rth and a constant temperature source TconstG are set in the thermal model, and heat sinks Heat Sink1 to Heat Sink6 are configured for each power device.

[0036] Combination Figure 2 As shown, the DC voltage source V_dc forms a split bus with the bus capacitors C1 and C2 via voltage divider resistors R2 and R3, supplying power to the primary-side GaN switching network. The primary-side GaN switching network includes multiple GaN power units, which are not directly electrically connected in parallel. The GaN half-bridge circuit includes an upper-side GaN power switch and a lower-side GaN power switch. The gates of the upper-side and lower-side GaN power switches respectively receive complementary control signals from the control unit.

[0037] The primary-side power stage consists of multiple GaN power switching devices, labeled FETD, FETD1, FETD2, FETD3, FETD4, FETD5, FETD6, and FETD7. These devices form multiple half-bridge structures: for example, the upper bridge arm consists of FETD and FETD2 forming one half-bridge, and the lower bridge arm consists of FETD3 and FETD7 forming another half-bridge; the other bridge arm, in conjunction with these, consists of FETD1 / FETD4 and FETD5 / FETD6, respectively. The drive signals s1 and s2 output by the control unit are complementary drive pulses (e.g., ...). Figure 5 As shown in the diagram, the corresponding upper and lower transistors are driven respectively, so that each branch forms a controllable high-frequency resonant current in Lr, Lr1, Lr2, and Lr3. Using a half-bridge topology and complementary drive signals, the DC input can be efficiently converted into high-frequency AC energy. Soft switching is achieved through the resonant network, reducing switching losses.

[0038] The input of each power transmission channel is connected to the output of the corresponding GaN power unit. Each power transmission channel is independent and has no direct electrical connection to the others. Figure 1 and Figure 5In the topology shown, each switch branch is connected to the resonant capacitor Cr via resonant inductors Lr, Lr1, Lr2, and Lr3, respectively, thus forming a "non-direct parallel" power bus mode under the impedance isolation of the resonant branches.

[0039] The power superposition unit is connected to the output terminal of each power transmission channel and is used to superimpose the power transmitted by each power transmission channel and output it to the load. In this embodiment, the power superposition unit is implemented by a high-frequency transformer Tr3. The resonant current flows into the primary side of the high-frequency transformer Tr3 after being sampled by the current measuring element Am1. Tr3 is used to realize electrical isolation and voltage transformation, and its secondary side is connected to the subsequent synchronous rectification unit.

[0040] like Figure 3 The diagram shows the logic for generating the drive signals. The control unit is connected to each GaN power unit and sends control signals to each GaN power unit. The control unit generates a reference signal through Constant and Ramp, which is then adjusted by Saturation and Gain modules before being input to Variable Frequency PWM for PWM modulation. The PWM output is delayed (dead time) by Turn-on Delay and Turn-on Delay 1, and then driven by Logical Operator NOT, resulting in two gate drive signals s1 and s2. Signals s1 and s2 are used to drive the GaN power unit. Figure 1 The GaN switching devices in the circuit drive the corresponding upper and lower transistors respectively, so that each branch forms a controllable high-frequency resonant current in Lr, Lr1, Lr2, and Lr3; Scope1 is used to observe the driving waveform.

[0041] like Figure 4 The key simulation waveforms shown are verified. Figure 4 (a) in the figure is the resonant current waveform, with time on the horizontal axis and amplitude on the vertical axis. The amplitude is large during the start-up phase, and then gradually decays and enters a steady state. Figure 4 In Figure (b), the output voltage waveform is shown, with time on the horizontal axis and output voltage on the vertical axis. After charging C, the voltage gradually builds up and stabilizes at approximately 400V. By eliminating current unevenness, the operating state of each power unit is ensured to be balanced, and the output power is stably superimposed, meeting the stable high power requirements of tilt-rotor UAVs during climb and other phases. Simulations and experiments demonstrate that this topology can maintain stable output voltage, low ripple, and fast dynamic response under different load conditions.

[0042] By constructing independent GaN power units and independent power transmission channels, with no direct electrical parallel connection between the units, a circuit structure of switch branch—resonant inductor—bus node is formed, achieving branch impedance decoupling and eliminating the problems of on-resistance drift and parallel current imbalance caused by dynamic resistance degradation. Even if the on-resistance of a single GaN power unit drifts due to dynamic resistance degradation, this change will not affect other units through the electrical path, thus avoiding on-resistance drift and parallel current imbalance problems at the topology level. At the same time, the control unit does not require complex current sharing algorithms; simple temperature equalization can achieve natural current sharing among the units, significantly reducing the complexity and cost of the control system.

[0043] In one embodiment, the power transmission path includes a high-frequency transformer or a coupled inductor; wherein the high-frequency transformer and the coupled inductor are formed by magnetic cores and windings.

[0044] like Figure 5 The diagram shows an enlarged view of the resonant network (power transmission channel) and the high-frequency transformer section. The resonant network consists of resonant inductors Lr, Lr1, Lr2, and Lr3 and a resonant capacitor Cr. The right ends of the multiple resonant inductors (each corresponding to a power transmission channel) converge and are connected in series with Cr, forming a non-directly parallel power combining point. The resonant current is sampled by the current measuring element Am1 and flows into the primary side of the high-frequency transformer Tr3. Tr3 is used to achieve electrical isolation and voltage transformation, and its secondary side is connected to the subsequent synchronous rectification unit.

[0045] In this embodiment, the power transmission channel can be implemented using a high-frequency transformer or a coupled inductor. When using a high-frequency transformer, the core material is selected from ferrite or amorphous materials with excellent high-frequency characteristics, and the winding uses Litz wire to reduce high-frequency losses. When using a coupled inductor, multiple inductors can be integrated on the same core, and the coupling effect of the magnetic circuit can be used to further reduce the size of the magnetic components. By selecting the parameters of Lr / Lr1 / Lr2 / Lr3 and Cr and coordinating with frequency conversion modulation, the system can achieve low switching losses and controllable power transmission within a suitable frequency range.

[0046] By using high-frequency transformers or coupled inductors as the core components of the power transmission channel, high-frequency energy transmission and electrical isolation can be effectively achieved. At the same time, magnetic integration technology can further reduce the size of magnetic components and improve the power density of the system.

[0047] In this embodiment, the power signal superimposed by the power superposition unit is transmitted to the load through a high-frequency transformer. The power superposition unit is the bus connection node of the high-frequency transformer, and the output terminals of each power transmission channel are connected in parallel to the bus connection node. The output terminals of each power transmission channel are respectively connected to different winding taps or different primary windings of the primary winding of the high-frequency transformer, and the secondary winding of the high-frequency transformer is used to connect the load.

[0048] like Figure 5 As shown, the right ends of the multiple resonant inductors Lr, Lr1, Lr2, and Lr3 are combined and connected in series with the resonant capacitor Cr to form a power combining point. This combining point serves as a bus connection node, connected to the primary winding of the high-frequency transformer Tr3. By connecting the output ends of multiple power transmission channels in parallel on the primary winding of the transformer, the natural superposition of multiple power sources is achieved. The secondary winding of transformer Tr3 enters the synchronous rectification unit via coupling capacitor C3. The synchronous rectification consists of FETD8, FETD9, FETD10, and FETD11, and a filter capacitor C is connected in parallel on the output side to form a DC output.

[0049] The superposition of multiple power sources is achieved by using a single connection node on the primary side of a high-frequency transformer. The structure is simple and easy to implement. The transformer also provides electrical isolation to ensure safe isolation between the primary power unit and the secondary load.

[0050] like Figure 6 The enlarged schematic diagram of the secondary-side synchronous rectification and output filtering section is shown. This embodiment provides a detailed description of the secondary-side synchronous rectification and output filtering structure. The secondary winding of transformer Tr3 enters the synchronous rectifier bridge via coupling capacitor C3. The synchronous rectifier bridge consists of FETD8, FETD9, FETD10, and FETD11, which are respectively installed on Heat Sink5 and Heat Sink6. An output filter capacitor C is connected in parallel to the synchronous rectification output terminal to form a DC output. A voltage measuring element Vm1 is connected in parallel to the output terminal to sample the output voltage and send it to the Scope for display. Figure 6 The Module shown here is a schematic diagram of the packaging and terminal definition of a synchronous rectification module.

[0051] In this embodiment, the control unit includes a main controller and multiple sub-controllers. The main controller calculates the total power command based on the load demand and distributes the total power command to the multiple sub-controllers according to a preset strategy. The preset strategy is a power equalization distribution strategy based on the temperature feedback of each GaN power unit. Each sub-controller controls one GaN power unit and generates a corresponding drive pulse according to the distributed power command. The drive pulse is used to control the upper and lower GaN power switching devices of a GaN half-bridge circuit.

[0052] In the specific implementation, the main controller collects the feedback value of the output voltage Vm1, compares it with the target voltage value, and calculates the total power command required by the system using algorithms such as a PI regulator. Subsequently, based on the temperature information fed back by each power unit, the main controller proportionally distributes the total power command to each sub-controller. For example, a larger power share is allocated to units with lower temperatures, and a smaller power share is allocated to units with higher temperatures, thereby achieving thermal balance among the units. After receiving the power command, each sub-controller generates corresponding drive pulses through frequency conversion modulation or phase shift modulation to control the switching action of the corresponding GaN half-bridge circuit.

[0053] The preset strategy is a balanced allocation strategy based on temperature feedback from each power unit, where the power is distributed to units with lower temperatures. The power unit handles a higher proportion of the power, achieving thermal balance.

[0054] A hierarchical control architecture with a central controller and sub-controllers decouples power distribution from drive generation. A temperature-feedback-based power balancing strategy actively adjusts the thermal stress distribution of each unit, preventing localized overheating and further improving system reliability. No complex current sharing algorithm is required; simple temperature-balanced distribution achieves natural current sharing among units, significantly reducing the complexity and cost of the control system.

[0055] In this embodiment, each GaN power unit includes a protection circuit (not shown in the accompanying drawings) to monitor the operating status of the corresponding GaN power unit and perform protection operations when the operating status is abnormal. Each GaN power unit is configured with an independent protection circuit (not shown separately in the figures). The protection circuit monitors key parameters such as current, voltage, and temperature of the unit in real time. When the monitored parameters exceed a preset safety threshold, the protection circuit immediately performs protection operations, such as shutting down the drive pulse or triggering a soft shutdown, to prevent the fault from escalating. By setting up independent protection circuits, each power unit has the ability to self-heal from faults, avoiding the impact of a single unit's failure on the normal operation of other units, and enhancing the fault tolerance of the system.

[0056] For example, the protection circuit includes an overcurrent protection circuit and an overtemperature protection circuit, which are used to shut down the drive pulse of the corresponding GaN power unit and upload the fault signal to the control unit when an overcurrent or overtemperature fault is detected in any GaN power unit.

[0057] Overcurrent protection circuits can be implemented by connecting a current sensing resistor in series in the power circuit or by using a current transformer. When the detected current exceeds the threshold, the comparator flips, triggering the hardware shutdown logic. Overtemperature protection circuits can be implemented by installing a temperature sensor (such as an NTC thermistor) on the surface of the power device or on the heat sink. When the temperature exceeds the set value, the protection action is also triggered. When the protection action occurs, the protection circuit first blocks the drive pulse of the unit, ensuring reliable shutdown of the GaN device, and simultaneously uploads the fault signal to the control unit through an optocoupler or isolated communication interface.

[0058] Overcurrent and overtemperature are the main failure modes of GaN devices. By setting up dedicated hardware protection circuits, a rapid response can be achieved within microseconds of the occurrence of a fault, effectively protecting power devices from damage and avoiding excessive thermal stress caused by local overcurrent. The heat distribution of each unit is uniform, extending the overall lifespan of the system.

[0059] In addition, the control unit is also used to update the power allocation command based on the number and capacity of the remaining GaN power units that are in normal working condition after receiving a fault signal.

[0060] When the main controller of the control unit receives a fault signal reported by a sub-controller, it first identifies the faulty unit's number and fault type. Then, the main controller removes the faulty unit from the healthy unit list and recalculates the power allocation command based on the total capacity of the remaining healthy units. For example, if the system originally has N power units, each with a rated power of P, and a total power requirement of P_total, when M units fail, the remaining NM healthy units must bear all the power. The main controller distributes P_total evenly (or according to strategies such as temperature) to the remaining units, ensuring the system continues to operate stably in derating mode.

[0061] By setting up protection circuits for protection and fault alarms, the system achieves fault-tolerant operation capability. In high-reliability application scenarios such as aviation power supplies, when a certain unit fails, the system can automatically reconfigure to maintain stable output voltage and ensure that critical loads such as UAVs can return safely. The fault-tolerant design ensures that the failure of a single unit does not affect the continuous operation of the system, greatly improving the mission reliability of the system.

[0062] like Figure 7 As shown, the over-temperature protection circuit includes: a constant temperature source (TconstG) for outputting a target temperature signal according to the control signal of the control unit; and a thermal resistor (Rth) corresponding to each GaN power unit for adjusting the temperature of each GaN power unit to the target temperature according to the target temperature signal.

[0063] Each GaN power unit is equipped with an independent heatsink, such as Heat Sink1 to Heat Sink4, to ensure even heat distribution. The number of GaN power units is determined by the target output power level. When the system power level needs to be increased, only standard modules and their corresponding power transmission magnetic components need to be added, and their outputs are connected to the system output terminal to achieve power superposition. No modification to the main circuit and control software is required, enabling flexible power expansion. In addition, the secondary-side GaN half-bridge units are also equipped with independent heatsinks, such as... Figure 7 Heat Sink5 and Heat Sink6.

[0064] In practical applications, this thermal model can be implemented using an active cooling system (such as a fan or liquid cooling plate) in conjunction with a PID control algorithm, stabilizing the operating temperature of each power unit near the target value. The thermal model, constructed using a constant temperature source and thermal resistance, enables closed-loop temperature control of each power unit, ensuring that each unit operates within a suitable temperature range and avoiding differences in dynamic resistance degradation caused by uneven temperature distribution. This assists in achieving current sharing from a thermal management perspective.

[0065] In this embodiment, the GaN power unit, drive circuit, and protection circuit can be designed as standardized modules; for example, to facilitate system expansion and maintenance, the GaN power unit, drive circuit, and protection circuit can be integrated into a standard power module.

[0066] This standard module features standardized mechanical dimensions, electrical interfaces, and communication protocols. External interfaces include: power input terminals (positive and negative), power output terminals (connected to the primary side of the transformer), auxiliary power supply terminals (powering the internal drive power supply), and a communication interface (receiving control commands and uploading status information). When a system power level needs to be increased, simply add the standard module and its corresponding power transmission magnetic components, connecting their outputs to the system output to achieve power superposition. No modifications to the main circuit or control software are required, enabling flexible power expansion. The number of units can be flexibly increased or decreased according to power level requirements.

[0067] The standardized power unit design allows for flexible addition or removal of units to meet power level requirements, enabling smooth power expansion. Newly added units are plug-and-play, eliminating the need to redesign the main circuitry and control software, thus shortening the development cycle and reducing R&D costs.

[0068] Based on the same application concept, this embodiment also provides a DC-DC converter, which includes a non-directly parallel GaN power module topology as described in any of the above embodiments.

[0069] Taking the high-density DC power supply of a range-extended tiltrotor UAV as an example, the non-direct parallel topology structure of the present invention is adopted to combine multiple GaN power modules in a non-direct parallel manner to meet the design requirements of 40kW output power and ≥12kW / L power density, thereby meeting the stringent requirements of aviation power supply for size and weight.

[0070] During the vertical takeoff phase of the drone, all power units work simultaneously to provide maximum power output and ensure stable 800V bus voltage. During the cruise phase, power demand decreases, and the control unit automatically shuts down some units according to the load rate, allowing the remaining units to operate in the high-efficiency range and improving light-load efficiency. When a unit stops due to a fault, the control unit automatically redistributes power to the healthy units, and the system operates at reduced derating but maintains stable output voltage to ensure the drone can return safely.

[0071] Furthermore, the topology of this application is not only suitable for tilt-rotor UAV power systems, but can also be widely used in high-power power electronic conversion applications that require high reliability and high power density, such as new energy vehicle charging piles, energy storage converters, data center power supplies, and industrial power supplies.

[0072] By adopting the non-directly parallel GaN power module topology of this application, the problems of dynamic resistance degradation and current unevenness caused by direct parallel connection of GaN devices are effectively solved, significantly improving the reliability and stability of the power supply system and meeting the stringent requirements of aerospace applications for high reliability and high power density.

[0073] In the foregoing description of this application, unless otherwise expressly specified and limited, the terms "fixed," "installed," "connected," or "linked" should be interpreted broadly. For example, the term "linked" can refer to a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; or it can refer to the internal communication of two components or the interaction between two components. Therefore, unless otherwise expressly limited in this application, those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0074] Based on the above description of this application, those skilled in the art will also understand that terms used, such as "upper," "lower," "length," "width," "top," "bottom," "inner," "outer," "axial," "longitudinal," "transverse," "clockwise," or "counterclockwise," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings of this application. These terms are used only for the purpose of facilitating the explanation of the application and simplifying the description, and are not intended to imply that the device or element involved must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the aforementioned orientation or positional relationship terms should not be understood or interpreted as limitations on the application.

[0075] Furthermore, the terms "first" or "second," etc., used in this application to refer to numbers or ordinal numbers are for convenience of description only and should not be construed as explicitly or implicitly indicating relative importance or specifying the number of indicated technical features. Also, a feature specified as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, or more, unless otherwise explicitly specified.

[0076] While numerous embodiments of this application have been shown and described herein, it will be appreciated by those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will arise in the mind and spirit of this application without departing from its intent. It should be understood that various alternatives to the embodiments of this application described herein may be employed in the practice of this application. The appended claims are intended to define the scope of protection of this application and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A non-directly parallel GaN power module topology, characterized in that, include: At least two independent GaN power units, each GaN power unit includes a GaN half-bridge circuit, and there is no direct electrical parallel connection between the GaN power units; Each GaN power unit has a power transmission channel corresponding to it. The input terminal of each power transmission channel is connected to the output terminal of the corresponding GaN power unit, and there is no direct electrical connection between the power transmission channels. A power superposition unit is connected to the output terminal of each of the power transmission channels, and is used to superimpose the power transmitted by each power transmission channel and output it to the load; The control unit is connected to each of the GaN power units and is used to send control signals to each of the GaN power units.

2. The non-directly parallel GaN power module topology according to claim 1, characterized in that, The power transmission channel includes a high-frequency transformer or a coupled inductor; wherein the high-frequency transformer and the coupled inductor are formed by a magnetic core and windings.

3. The non-directly parallel GaN power module topology according to claim 2, characterized in that, The power superposition unit is a bus connection node of a high-frequency transformer, and the output terminals of each power transmission channel are connected in parallel to the bus connection node; wherein, the output terminal of each power transmission channel is respectively connected to different winding taps or different primary windings of the primary winding of the high-frequency transformer, and the secondary winding of the high-frequency transformer is used to connect the load.

4. The non-directly parallel GaN power module topology according to claim 1, characterized in that, The GaN half-bridge circuit includes an upper GaN power switch and a lower GaN power switch, the gates of which respectively receive complementary control signals from the control unit.

5. The non-directly parallel GaN power module topology according to claim 4, characterized in that, The control unit includes: The main controller is used to calculate the total power command according to the load demand and distribute the total power command to multiple sub-controllers according to a preset strategy; wherein, the preset strategy is a power equalization distribution strategy executed based on the temperature feedback of each GaN power unit; Each of the sub-controllers controlling the GaN power units is used to generate corresponding drive pulses according to the assigned power command; wherein, the drive pulse is used to control the upper GaN power switch and the lower GaN power switch of a GaN half-bridge circuit.

6. The non-directly parallel GaN power module topology according to claim 1, characterized in that, Each GaN power unit includes a protection circuit for monitoring the operating status of the corresponding GaN power unit and performing protection operations when the operating status is abnormal.

7. The non-directly parallel GaN power module topology according to claim 6, characterized in that, The protection circuit includes an overcurrent protection circuit and an overtemperature protection circuit, which are used to shut down the drive pulse of the corresponding GaN power unit and upload the fault signal to the control unit when an overcurrent or overtemperature fault is detected in any GaN power unit.

8. The non-directly parallel GaN power module topology according to claim 7, characterized in that, The control unit is also used to update the power allocation command based on the number and capacity of the remaining GaN power units that are in normal working condition after receiving a fault signal.

9. The non-directly parallel GaN power module topology according to claim 7, characterized in that, The over-temperature protection circuit includes: A constant temperature source is used to output a target temperature signal according to the control signal from the control unit. A thermal resistor corresponding to each GaN power unit is used to adjust the temperature of each GaN power unit to the target temperature according to the target temperature signal.

10. A DC-DC converter, characterized in that, Includes the non-directly parallel GaN power module topology as described in any one of claims 1-9.

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